The present invention relates to a tension retaining device for use on a strapped bulk unit load. More particularly, the present invention relates to a biased strap tension retaining device for maintaining the tension in a strapped bulk unit load when the bulk unit normally increases or decreases in size.
Material bulk unit loads (products) are often unitized or strapped to facilitate handling of the bulk unit loads. As is often the case, there may be a large quantity of products, for example, stacked on and strapped to a pallet. Sometimes, in order to more efficiently store or warehouse the products, pallets of goods are stacked onto one another.
In the event that the products are stable in size, there is generally no concern with such stacking. However, when the products are not stable in size i.e. compressible or expandable, the straps may loosen or tighten (due to changes in the volume of products), and as a result the bulk unit load may no longer be stable. While this may not be problematic for certain products, however, it can be quite problematic for other products.
There are also certain products that are compressible. That is, when multiple pallets are stacked on one another, the product compress to a minimal extent, although they appear (visually) not to have undergone any compression at all. For example, plastic (polyethylene terephthalate or PET) beverage bottles are often shipped to a bottler on a pallet in multiple layers (bulk unit). In that the empty bottles are light-weight, the bulk units can be stacked on one another for storage.
When bulk units are stacked, the compression on the lower or bottom bulk units results in slack developing in the strap. An increase or decrease in bulk unit height can also occur due to product expansion or contraction. This can also be viewed as a reduction or enlargement in the perimeter of the bulk unit load. The reduction (or occurrence of slack) can be problematic in that the strap material may no longer retain the products in compression. As such, the bulk unit load may become unstable and the product can easily fall out of the bulk unit. In addition, an enlargement in the product may cause product damage from excessive strap tension or exceed the strap burst strength, resulting in unstable conditions.
Accordingly, there is a need for a strap tension retaining device for use on a strapped bulk unit load. Desirably, such a device facilitates the strap retaining an acceptable range of tension following a reduction or enlargement of the bulk unit load. More desirably, such a device is small in size, and is fabricated from readily available materials in a cost effective manner.